Ceiling panel structure



D. DEAKINS;v 3,333,387

Aug. l, 1967 CEILING PANEL STRUCTURE Filed Aug. 27, 1965 jj (f6 @Tw Y c fw United States Patent O 3,333,387 CELING PANEL STRUCTURE Donald Deakins, 7206 Rue Godbout, Palos Verdes, Calif. 90274 Filed Aug. 27, 1965, Ser. No. 483,080

16 Claims. (Cl. 52-664) s This invention has to do with a suspended ceiling panel structure and is more particularly concerned with a novel translucent panel and acoustical ceiling board supporting framework adapted to be suspended from a ceiling, in spaced relationship therebelow.

It is common practice in modern building construction an-d design to provide a false ceiling of translucent panels in a room, in spaced relationship below the true ceiling of the room and below lighting fixtures mounted on the ceiling, whereby the entire false ceiling or a large por tion thereof is illuminated and provides the room with full, soft, diffused light. The translucent or acoustical board panels are of limited dimension or extent and are supported by egg crate-like frameworks established of wood or metal and suspen-ded from the ceiling by suitable hanger means. The frameworks establish a plurality of .rectangular openings corresponding in size and shape with the translucent or acoustical board panels. Each opening in the framework is provided with an upwardly disposed stop shoulder about its perimeter to engage and -support the edge portions of the panel related thereto.

With the relationship of parts set forth above, the panels can be advantageously pushed up, or lifted from engagement in their related openings in the framework to provide access to the lighting fixtures and to facilitate cleaning the panels.

In the case of wood .frameworks of the general character referred to, the several boards going to make up the structure are suitably 4glued and nailed or screw fastened together to establish a fixed permanent installation. The establishment of such a construction is difficult, time consuming and is costly.

In the case of `metal frameworks of the general character referred to, metal T sections or extrusions are ernployed. The sections or extrusions are cut into predetermined lengths and are secured together by welding or by means of screw fasteners. In the cases where screw fasteners are employed, suitable Iholes must be drilled or otherwise established in the sections to receive the fasteners. Further, suitable sheet metal corner blocks, gus sets, and other like brackets, with fastener receiving openings are generally provided to tie and couple the sections or extrusions together.

It will be apparent that the establishment of such metal frameworks is complicated, requires the exercise of great or considerable skill, is time consuming and is extremely costly.

The hanging or hanger means ordinarily employed to suspend such frameworks from -their related ceilings involve 'the establishment of openings in the frameworks, at spaced stations throughout their plan-ar extent and through which hanger wires, fixed to and depending from the ceiling, are engaged and suitably bent or twisted.

Ordinarily, the ceiling of the room is a rather thin, non-load supporting structure of lath and plaster or the like, supported by spaced ceiling rafters or beams. Accordingly, the hanger means or wires must be anchored to the beams or rafters and placement or spacing of the wire hangers is limited or restricted to those lines along which the -rafters or ceiling beams occur. As a result of the above, the hanger wires are ordinarily installed first. Then the openings in the framework are established to fice occur below the wires and to receive the wires when the framework is elevated and positioned below the ceiling. This procedure, while necessary, is extremely difficult and undesirable.

An object of this invention is to provide a novel metal framework construction of the general character referred to comprising a plurality of like elongate sections which framework does not require the establishment of openings in the sections `and the application or installation of screw fasteners and the like therein, in its fabrication.

It is another object of this invention to provide a framework of the character referred to comprising sections having special channel means therein and including a plurality of novel, like, metal clips or couplers adapted to cooperatively engage in and with the channel means of adjacent, related channels.

A further object of this invention is to provide `a construction of the character referred to having novel hanger means `for supporting the framework 'from an-d below a ceiling structure or the like.

The various objects and features of my invention will -be fully understood from the following -detailed description of a typical preferred form and application of my invention, throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is an isometric view of a portion of a room showing my new construction related thereto;

FIG. 2 is an isometric View of a portion of one section and a coupler, said coupler being arranged preparatory to engagement with the section;

FIG. 3 is an isometric View showing the coupler engaged with the section and showinganother section and coupler assembly related thereto;

FIG. 4 is an enlarged sectional view taken as indicated by line 4 4 on FIG. 3

FIG. 5 is an enlarged sectional view taken as indicated by line 5-5 on FIG. 3;

FIG. 6 is an isometric view of a hanger plate as provided by this invention; and,

FIG. 7 is a side elevational View showing the'hanger plate engaged with a section.

The ceiling panel structure that I provide and which is illustrated in the accompanying drawing includes, a plurality of elongate, horizontal primary sections S arranged in lateral spaced, parallel relationship and hung in spaced relationship below a ceiling A in a room R by hanger means H, a plurality of elongate, horizontal secondary sections S' arranged in lateral spaced relationship with their axes at right angles to or normal to the axes of the sections S, to extend between the adjacent primary sections at the ends thereof or intermediate their ends, as circumstances require or as desired.

The construction further includes coupling means M -releasably securing the ends of the several sections S and S to their related or adjacent sections, and hanger means H to support sections S' .below the ceiling A. The several secti-ons cooperate to define an egg crate-like framework having a plurality of square or rectangular panel receiving openings O.

The construction that I provide further includes a translucent lor transparent panel P established of glass, plastic, acoustical ceiling board or other suitable material, for each opening O.

The sections S and S are alike in cross section and are preferably in the form of aluminum extrusions, although they might, in practice, be established of other suitable materials and by other suitable methods.

Each section is in the nature of an inverted T section having a central, fiat, vertical, longitudinally extending base 11 formed intricately with the lower edge of the web,

along the central longitudinal axis of the base. The base cooperates with the web to define laterally outwardly projecting flanges F at each side of the web, which flanges have flat, upwardly disposed, panel supporting surfaces 12 and straight longitudinal outer side edges.

In addition to the foregoing, each section further includes an upwardly projecting rib 13, of limited vertical extent on each fiange F, in lateral spaced relationship from the web and cooperating therewith to define an upwardly opening, longitudinally extending, lower channel The upper edge of the web is provided with a flat, horizontal header 15 of limited lateral extent and projecting laterally from the opposite sides of the web.

The header 15 has downwardly extending or depending longitudinal flanges 16 of limited Vertical extent along its outer longitudinal side edges, which flanges cooper-ate with the header and their adjacent sides of the web to define downwardly opening, longitudinally extending, upper channels 17 at and along the opposite sides of the webs.

The downwardly opening, longitudinally extending upper channels 17 are spaced from and oppose the upwardly opening, longitudinally extending, lower channels 14 at the lower edge porti-on of the web and cooperate to define channel means C, at each side of the web, to cooperate with the means M, as will hereinafter be described.

The ends of the sections S yand S' are cut to define fiat ends 18, which occur in a plane normal to the longitudinal axes of the sections.

The coupling mea-ns M is adapted to releasably couple the end of each section to one side of its related, adjacent section, at a point intermediate the ends of said related adjacent section, with the end 18 of the base portion or flanges F of the first section in fiat, butted engagement with the outer, opposing edge of the second mention section, as clearly illustrated in FIGS. 3 and 5 of the drawings.

The means \M includes an elongate coupling D formed of sheet metal, having a fiat, vertical, plate-like inner portion 20 with straight, parallel top and bottom edge portions 21 `and 22. The portion 20 corresponds in lateral extent with the lateral extent of the upper :and lower channels 17 and 14 of the section and corresponds in vertical extent with the distance between the bottoms of the said sections 17 and 14. The inner portion 20 of the coupling or coupler is adapted to be slidably engaged into engagement with a pair of related channels 17 and 14 and adjacent their related side of their related web 10, from one end of the section with which the coupling is related, as clearly illustrated in FIGS. 3, 4 and 5 of the drawings.

The inner portion 20 is of sufficient longitudinal extent and is so fitted .in or with its related channels that it is effectively frictionally held and is held against vertical and/ or lateral shifting or pivoting relative to the section.

In the preferred carrying out of the invention and as illustrated in the drawings, the upper edge of the inner portion 20 is notched, as at 23 and the stock displaced or moved to define the notch is formed or bent laterally outwardly from the plane of the coupling and at that side of the coupling which occurs adjacent the related web 10 of the section, to define a stop tab 24. The stop tab 24 is adapted to engage the adjacent end 18 of the section and to limit engagement of the coupling in or with the channel means C.

The notch 23 occurs longitudinally inward of the tab 24 and is adapted to accommodate the end portion of the fiange 16 related thereto, which portion of the flange is or can be advantageously bent or otherwise urged into engagement in the notch, as illustrated in FIG. 3 of the drawings. It will be apparent that when the end portion of the flange 16 is urged into engagement in the notch 23, the coupling is suitably locked in position in the channel means and is held against longitudinal outward displacement therefrom.

The notch 23 and tab 24, therefore, establish an effective locking means to limit engagement of the inner portion of the coupling with its related section and prevent its accidental displacement therefrom.

The coupling D further includes a flat, vertical, elongate outer portion 25, equal in vertical extent with the outer portion 20 and corresponding in longitudinal extent with the lateral extent of the fianges F of the sections.

The upper. outer edge portion of the outer portion 25 is notched as at Z6 to cooperatively receive the fiange 16 of a related section, as will hereinafter be described.

The outer end of the outer portion 25 is provided with a fiat, vertically extending, laterally projecting, fiange-like cleat 27, which cleat is formed intricately with or on the coupling by a suitable bending operation. The cleat 27 is of limited lateral extent and is adapted to be engaged in and between the upper and lower channels 17 and 14 of a related section S or S'.

The means M also includes stops 31 in the upper channels 17, each of which is established by piercing and urging a portion of the fiange 16 laterally inwardly (see FIGS. 2, 3 and 5 of the drawings).

The stops 31 are arranged to occur above the notches 30.

Still further, the means M includes laterally inwardly projecting detents 32 in predetermined spaced relationship from each stop 31 and adapted to engage the upper end portion of a cleat to yieldingly hold it against the stop.

The detents 32 are established by suitably dimpling the flange 16, laterally inwardly.

In operation, when it is desi-red to couple the end of a first or one `section S to the side of another or second section S, a coupling D is engaged with the first section, as set forth above. The upper portion of the first section and its related coupling are then rotated laterally and downwardly slightly and the lower edge of the outer portion of the coupling is engaged in a predetermined, desired notch 30 in the second section and so that the cleat 27 occurs adjacent the web 10 of the second section. The upper portion of the first section and its Irelated coupling are then rotated back, or laterally, inwardly and upwardly and in such a manner that the upper end of the cleat 27 enters the upper channel 17. The first section and its related coupling are rotated or advanced so that the cleat is yieldingly urged by the detent 32 and into stop engagement against the stop 31.

When the first and second sections S and S have been related in the manner set forth above, it will be apparent that the first and second sections are suitably releasably coupled together with the ends of the iianges F of the first section in butted engagement with the side edge of the adjacent flange F of the second section.

In practice, the sections S and S can be made or established in predetermined, standard lengths and the notches 30, stops 31 and detents 32 can be established at predetermined spaced intervals throughout the longitudinal extent of the sections and in such a manner that an egg crate-like panel engaging and supporting framework, establishing panel receiving openings of predetermined size or extent, in a predetermined pattern, can be easily and quickly established, without the exercise of special Vskills and without the use of screw fasteners and the like.

The hanger means H that I provide includes a plurality of fiat, elongate, vertically extending sheet metal hanger plates 40 having apertured upper portions 41 adapted to be coupled with suitable hanger wires W fixed to and depending from the ceiling structure A and having lower portions 42 adapted to releasably engage in and with the channel means C of the sections S and S' occurring below the wires.

The lower portions 42 of the plates 40 are adapted to occur in spaced parallel relationship with the webs of the sections S or S with which they are related and laterally outward of the flanges 16 of the sections. The lower edges 43 of the lower portions are bent laterally inwardly towards the webs and then downwardly and are adapted to enter and establish seated engagement in the lower channels 14. The upper ends of the lower portions are provided with laterally inwardly oilset, upwardly disposed stop tabs 44, at one side or edge ofthe plate, which tabs enter and stop against the bottoms of the upper channels 17, when the plates are vertically disposed.

The lower corner or corners of the plates, occurring below the tabs 44, are radiused as at 45, to facilitate rotating or rocking the plates into engagement with the channel means C.

In operation, the lower end of the hanger wire W, which wire is suitably lixed to and depends from the ceiling A, is engaged through the apertured upper portion 41 of the hanger plate 40 and is suitably bent or twisted so that the plate is hung in predetermined spaced relationship below the ceiling A.

The lower end of the plate 40 is then pivoted laterally and upwardly so that the tab is positioned in the channel 17 of the section S and the radiused corner is positioned in the related channel 14. The upper end of the plate is then rotated back, laterally and upwardly, in the direction indicated by the arrow X in FIG. 7 of the drawings and until the lower edge portion 43 of the plate seats and stops on the bottom of the channel 14.

When the plate 40 is -thus engaged, it will be apparent that the section S is suitably supported from the ceiling A and that the hanger means is such that the section S cannot be accidentally disengaged or released.

It will be apparent that the means H provided by this invention is extremely simple, inexpensive to manufacture and dependable in operation, It is to be noted that the hanger means H that I provide does not require the exercise of any special skill for its operation or installation and does not require the establishment of special openings and the like in the sections S and S or the application of screw fasteners and the like.

It is to be noted that the flanges F of the several sections cooperating to define each panel receiving opening O project laterally inwardly about the entire perimeter of the opening and are so disposed as to advantageously engage and support the panel P to be related thereto.

Having described only a typical preferred form and application of -my invention, I do not wish to be limited to the specific details herein set forth, but wish to reserve to myself any modifications and variations that may appear to those skilled in the art and which fall within the scope of the following claims. v

Having described my invention I claim:

1. A framework of the character referred to including pairs of elongate, horizontal, parallel, primary sections having llat, vertical, longitudinal webs, tlat, horizontal, laterally outwardly projecting base flanges along the lower edges of the webs and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels being defined by the web, upper and lower longitudinal flanges of limited vertical extent and in lateral spaced relationship from the web and by tieing structure between the web and the said upper and lower llanges, said lower flanges having a plurality of longitudinally spaced, laterally and upwardly opening notches, said upper channel having a stop therein, above each notch in the lower flange, a plurality of elongate horizontal, laterally spaced, parallel, secondary sections arranged at right angle to and extending between related pairs of primary sections and having at, vertical, longitudinal webs, llat, horizontal, laterally outwardly projecting base flanges and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides ofthe web, said channels opening longitudinally outwardly at the opposite ends of the secondary sections, and coupler means releaseably securing the primary and secondary sections together including, an elongate coupler plate related to each end of each secondary section, each coupler plate having an inner section slidably engaged in a pair of related upper and lower channels at the open ends thereof, an outer portion projecting longitudinally outwardly from the secondary section to extend across the adjacent base flange of the related primary section and to extend through a related notch in the adjacent lower flange of the primary section, a laterally and upwardly opening notch in -the top of the outer portion to accommodate the adjacent upper flange of the primary section and a ilat vertically extending cleat on the outer edge of the outer portion with its lower end seated in the lower channel of the primary section and its upper end seated in the upper channel of the primary section and stopped against the related stop in the upper channel. A

2. A structure as set forth in claim 1 wherein, said coupler plates have laterally projecting tabs to engage the ends of the secondary sections and to limit longitudinal inward shifting of the coupler plates in the channels of thelsecondary sections.

3. Astructure as set forth in 'claim `1 wherein, said coupler plates have laterally opening retaining notches at the ends of the secondary sections, the ends of the upper llanges of the secondary sections being bent into engagement in the retaining notches to maintain the coupler plates in iixed longitudinal position with the secondary sections.

4. A structure as set forth in claim 1 wherein, said coupler plates have laterally projecting tabs to engage and stop against the ends of the secondary sections and have laterally outwardly opening retaining notches to receive the ends of the upper flanges dening the upper channels of the secondary sections, the ends of the said upper flanges being bent into engagement in the retaining notches.

5. A framework of the character referred to including pairs of elongate, horizontal, parallel, primary sections having llat, vertical, longitudinal webs, ilat, horizontal, laterally outwardly projecting base flanges along the lower edges of the webs and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels being defined by the web, upper and lower longitudinal flanges of limited vertical extent and in lateral spaced relationship from the web and by tieing structure between the web and the said upper and lower flanges, said lower flanges having a plurality of longitudinally spaced, laterally and upwardly opening notches, said upper channel having longitudinally spaced stops and detents therein, above each notch inthe lower ange, a plurality of elongate horizontal, laterally spaced, parallel, secondary sections arranged at right angle to and extending between related pairs of primary sections and having ilat, vertical, longitudinal webs, flat, horizontal, laterally outwardly projecting base flanges and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels opening longitudinally outwardly at the opposite ends of the secondary sections, and coupler means releaseably securing the primary and secondary sections together including, an elongate coupler plate related to each end of each secondary section, each coupler plate having an inner section slideably engaged in a pair of related upper and lower channels at the open ends thereof, an outer portion projecting longitudinally outwardly from the secondary rsection to extend across the adjacent base llanges of the related primary section and to extend through a related notch in the adjacent lower flange of the primary section, a laterally and upwardly opening notch in the top of the outer portion to accommodate the adjacent upper llange of the primary section and a flat vertically extending cleat on the outer edge of the outer portion with its lower end seated in the lower channel of the primary section and its upper end seated in the upper channel of the primary section and engaged between the related stop and detent.

6. A structure as set forth in claim wherein, said coupler plates have laterally projecting tabs to engage the ends of the secondary sections and to limit longitudinal inward shifting of the coupler plates in the channels of the secondary sections.

7. A structure as set forth in claim 2 wherein, said coupler plates have laterally opening retaining notches at the ends of the secondary sections, the ends of the upper flanges of the secondary sections being bent into engagement in the retaining notches to maintain the coupler plates in fixed longitudinal position with the secondary sections.

8. A structure as set forth in claim 2 wherein, said coupler plates have laterally projecting tabs to engage and stop against the ends of the secondary sections and have laterally outwardly opening retaining notches to receive the ends of the upper flanges defining the upper channels of the secondary sections, the ends of the said upper ilanges being bent into engagement in the retaining notches.

9. A framework of the character referred to including pairs of elongate, horizontal, parallel, primary sections having flat, vertical, longitudinal webs, flat, horizontal, laterally outwardly projecting base flanges along the lower edges of the webs and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels being dened by the web, upper and lower longitudinal flanges of limited Vertical extent and in lateral spaced relationship from the web and by tieing structure between the web and the said upper and lower flanges, said lower flanges having a plurality of longitudinally spaced, laterally and upwardly opening notches, said upper channel having a stop therein, above each notch in the lower flange, a plurality of elongate horizontal, laterally spaced, parallel, secondary sections arranged at right angle to and extending between related pairs of primary sections and having flat, vertical, longitudinal webs, flat, horizontal, laterally outwardly projecting base flanges and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels opening longitudinally outwardly at the opposite ends of the secondary sections, and coupler means releaseably securing the primary and secondary sections together including, an elongate coupler plate related to each end of each secondary section, each coupler plate having an inner section slideably engaged in a pair of related upper and lower channels at the open ends thereof, an outer portion projecting longitudinally outwardly from the secondary section to extend across the adjacent base flange of the related primary section and to extend through a related notch in the adjacent lower flange of the primary section, a laterally and upwardly opening notch in the top of the outer portion to accommodate the adjacent upper flange of the primary section and a flat vertically extending cleat on the outer edge of the outer portion with its lower end seated in the lower channel of the primary section and its upper end seated in the upper channel of the primary section and stopped against the related stop in the upper channel, and hanger means to engage a hanger wire fixed to and depending from a supporting structure to support the sections below said supporting structures and including, an elongate vertically extending hanger plate having an upper apertured portion to engage and connect with a hanger wire, a lower portion having a laterally offset, elongate horizontally extending lower edge portion engaged :and seated in the lower channel of its related section, and :a laterally offset upwardly projecting tab above one end of the lower edge portion .and engaged and seated in the vrelated upper qchanneiof nhe section.

coupler plates have laterally projecting tabs to engage the ends of the secondary sections and to limit longitudinal inward shifting of the coupler plates in the channels of said secondary sections.

11. A structure as set forth in claim 9 wherein, said coupler plates have laterally opening retaining notches at the ends of the secondary sections, the ends of the upper flanges of the secondary sections being bent into engagement in the retaining notches to ymaintain the coupler plates in xed longitudinal position with the secondary sections.

12. A structure as set forth in claim 9 wherein, said coupler plates have laterally projecting tabs to engage and stop against the ends of the secondary sections and have laterally outwardly opening retaining notches to receive the ends of the upper flanges of the secondary sections, the ends of the said upper flanges being bent into engagement in the retaining notches.

13. A yframework of the character referred to including pairs of elongate, horizontal, parallel, primary sections having flat, vertical, longitudinal webs, flat, horizontal, laterally outwardly projecting base flanges along the lower edges of the webs and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels being defined by the web, upper and lower longitudinal flanges of limited vertical extent and in lateral spaced relationship from the web and by tieing structure between the web and the said upper and lower flanges, said lower ilanges having a plurality of longitudinally spaced, laterally and upwardly opening notches, said upper channel having longitudinally spaced stops and detents therein, above each notch in the lower flange, a plurality of elongate horizontal, laterally spaced, parallel, secondary sections arranged at right angle to and extending between related pairs of primary sections and having flat, vertical, longitudinal webs, flat, horizontal, laterally outwardly projecting base flanges and vertically spaced downwardly and upwardly opening channels extending longitudinally along the opposite sides of the web, said channels opening longitudinally outwardly at the opposite ends of the secondary sections, and coupler means releaseably securing the primary and secondary sections together including, an elongate coupler plate related to each end of each secondary section, each coupler plate having an inner section slideably engaged in a pair of related upper and lower channels at the open ends thereof, an outer portion projecting longitudinally outwardly from the secondary section to extend across the adjacent base flanges of the related primary section and to extend through a related notch in the adjacent lower flange of the primary section, a laterally and upwardly opening notch in the top of the outer portion to accommodate the adjacent upper flange of the primary section and a flat vertically extending cleat on the outer edge of the outer portion with its lower end seated in the lower channel of the primary section and its upper end seated in the upper channel of the primary section and engaged between the related stop and detent, and hanger means to engage a hanger wire fixed to and depending from a supporting structure to support the sections below said supporting structures and including, an elongate vertically extending hanger plate having an upper apertured portion to engage and connect with a hanger wire, a lower portion having a laterally offset, elongate horizontally extending lower edge portion engaged and seated in the lower channel of its related section, and a laterally offset upwardly projecting tab above one end of the lower edge portion and engaged and seated in the related upper channel of the section.

14. A structure as set forth in claim 13 wherein, said coupler plates have laterally projecting tabs to engage the ends of the secondary sections and to limit longitudinal inward shifting of the coupler plates in the channels of said secondary sections.

15. A structure as set forth in claim 13 wherein, said r coupler plates have laterally opening retaining notches at the ends of the secondary sections, the ends of the upper llanges of the secondary sections being bent into engagement in the retaining notches to maintain the coupler plates in fixed longitudinal position with the secondary sections.

16. A structure as set forth in claim 13 wherein, said coupler plates have laterally projecting tabs to engage and stop against the ends of the secondary sections and have laterally outwardly opening retaining notches to receive the ends of the upper anges of the secondary sections, the ends of the said upper flanges being bent into engagement in the retaining notches.

References Cited UNITED STATES PATENTS Wakefield 52-484X Wilde 287-189.36 Mancini 52-484 Smith et al. 52-484X Tuten et al. 52-484X Van Buren 287-189.36

10 DAVID J. WILLIAMOWSKY, Primm Examiner.

P. C. KANNAN, Assistant Examiner. 

1. A FRAMEWORK OF THE CHARACTER REFERRED TO INCLUDING PAIRS OF ELONGATE, HORIZONTAL, PARALLEL, PRIMARY SECTIONS HAVING FLAT, VERTICAL, LONGITUDINAL WEBS, FLAT, HORIZONTAL, LATERALLY OUTWARDLY PROJECTING BASE FLANGES ALONG THE LOWER EDGES OF THE WEBS AND VERTICALLY SPACED DOWNWARDLY AND UPWARDLY OPENING CHANNELS EXTENDING LONGITUDINALLY ALONG THE OPPOSITE SIDES OF THE WEB, SAID CHANNELS BEING DEFINED BY THE WEB, UPPER AND LOWER LONGITUDINALLY FLANGES OF LIMITED VERTICAL EXTENT AND IN LATERAL SPACED RELATIONSHIP FROM THE WEB AND BY TIEING STRUCTURE BETWEEN THE WEB AND THE SAID UPPER AND LOWER FLANGES, SAID LOWER FLANGES HAVING A PLURALITY OF LONGITUDINALLY SPACED, LATERALLY AND UPWARDLY OPENING NOTCHES, SAID UPPER CHANNEL HAVING A STOP THEREIN, ABOVE EACH NOTCH IN THE LOWER FLANGE, A PLURALITY OF ELONGATE HORIZONTAL, LATERALLY SPACED, PARALLEL, SECONDARY SECTIONS ARRANGED AT RIGHT ANGLE TO AND EXTENDING BETWEEN RELATED PAIRS OF PRIMARY SECTIONS AND HAVING FLAT, VERTICAL, LONGITUDINALLY WEBS, FLAT, HORIZONTAL, LATERALLY OUTWARDLY PROJECTING BASE FLANGES AND VERTICALLY SPACED DOWNWARDLY AND UPWARDLY OPENING CHANNELS EXTENDING LONGITUDINALLY ALONG THE OPPOSITE SIDES OF THE WEB, SAID CHANNELS OPENING LONGITUDINALLY OUTWARDLY AT THE OPPOSITE ENS OF THE SECONDARY SECTIONS, AND COUPLER MEANS RELEASEABLY SECURING THE PRIMARY AND SECONDARY SECTIONS TOGETHER INCLUDING, AN ELONGATE COUPLER PLATE RELATED TO EACH END OF EACH SECONDARY SECTION, EACH COUPLER PLATE HAVING AN INNER SECTION SLIDABLY ENGAGED IN A PAIR OF RELATED UPPER AND LOWER CHANNELS AT THE OPEN ENDS THEREOF, AN OUTER PORTION PROJECTING LONGITUDINALLY OUTWARDLY FROM THE SECONDARY SECTION TO EXTEND ACROSS THE ADJACENT BASE FLANGE OF THE RELATED PRIMARY SECTION AND TO EXTEND THROUGH A RELATED NOTCH IN THE ADJACENT LOWER FLANGE OF THE PRIMARY SECTION, A LATERALLY AND UPWARDLY OPENING NOTCH IN THE TOP OF THE OUTER PORTION TO ACCOMMODATE THE ADJACENT UPPER FLANGE OF THE PRIMARY SECTION AND A FLAT VERTICALLY EXTENDING CLEAT ON THE OUTER EDGE OF THE OUTER PORTION WITH ITS LOWER END SEATED IN THE LOWER CHANNEL OF THE PRIMARY SECTION AND ITS UPPER END SEATED IN THE UPPER CHANNEL OF THE PRIMARY SECTION AND STOPPED AGAINST THE RELATED STOP IN THE UPPER CHANNEL. 